a. Field of the Invention
The present invention relates generally to systems providing stored thermal energy in the form of ice, and more specifically to refrigerant-based ice storage air conditioning systems used to provide cooling load during peak electrical demand.
b. Description of the Background
With the increasing demands on peak demand power consumption, ice storage has been utilized to shift air conditioning power loads to off-peak times and rates. A need exists not only for load shifting from peak to off-peak periods, but also for increases in air conditioning unit capacity and efficiency. Current air conditioning units having energy storage systems have had limited success due to several deficiencies including reliance on water chillers that are practical only in large commercial buildings and have difficulty achieving high-efficiency. In order to commercialize advantages of thermal energy storage in large and small commercial buildings, thermal energy storage systems must have minimal manufacturing costs, maintain maximum efficiency under varying operating conditions, emanate simplicity in the refrigerant management design, and maintain flexibility in multiple refrigeration or air conditioning applications.
Systems for providing thermal stored energy have been previously contemplated in U.S. Pat. Nos. 4,735,064, 4,916,916, both issued to Harry Fischer, U.S. Pat. No. 5,647,225 issued to Fischer et al., U.S. patent application Ser. No. 10/967,114 filed Oct. 15, 2004 by Narayanamurthy et al., U.S. patent application Ser. No. 11/112,861 filed Apr. 22, 2005 by Narayanamurthy et al., and U.S. patent application Ser. No. 11/138,762 filed May 25, 2005 by Narayanamurthy et al. All of these patents utilize ice storage to shift air conditioning loads from peak to off-peak electric rates to provide economic justification and are hereby incorporated by reference herein for all they teach and disclose.